I just purchased a 2001 F250 extended cab 7.3L Powerstroke. I knew from the get go that the engine was missing and not running 100%, but after doing some research I figured that it was something to do with the injectors and being mechanically inclined figured I could fix it myself.

The issue I'm having is hard to start, takes about 10-15 seconds to start after the "wait" light goes out and you turn the key. There is a puff of white smoke that comes out after it does start and it runs really rough for about a minute or so, then it idles just fine. When on the road it runs rough and when you are cruising at about 50 mph or so and you let off the accelerator and then back on to it, it has major hesitation.

I have removed the driver side valve cover gasket and inspected the injectors, I disconnected each one individually while the engine was running and the engine idle definitely changed as I disconnected each one, one by one.

While I had it open I did notice that the injectors are in the follow order from the front of the truck to the back: AD AE AD AD

I have read on one of the forums that the AE injector needs to be the last one closest to the firewall. Could this be the cause of my problem?

I have not taken the passenger side valve cover off as of yet, since it looks to be not as easy as the driver side.

I just took off the passenger side valve cover. The connector plug on both sides were both plugged in and secure. I did the quarter fix on both just to be safe.

When I disconnected each individual injector I did notice that the second one from the front made no change to the engine idle when disconnected. I'm thinking that the injector is probably bad. The other three when disconnected definitely made the engine run differently.

I also noticed white smoke coming out of somewhere in the valve compartment on both sides. Any ideas what this is?

Would one bad injector make the engine run crappy?

I guess since I have it apart I will replace all of the injectors, glow plugs, valve cover gaskets, and wiring harnesses. Any recommendations on rebuilt injectors, just want to go back with stock rebuilds.

Thanks for the response. Injectors are what I'm thinking as well. I do not have AE nor do I know anyone locally with it. That would definitely help me out in figuring out whats wrong. I have been reading the forums and I have seen a lot of posts about the CPS causing all sorts of problems, could it cause something like this?

Ok I switched injector #3 with injector #1 and the issue is still happening in the #3 spot. So I ruled out bad injector. Where should I go from here? Replace the wiring harness? How can I check at the wiring harness plug to see if it is sending power to that injector?

I switched out the UVC wire harness and low and behold, injector #3 is now doing what it is suppose to do. Truck is running great now. Only issue I am having now is when I step on the gas the SES light comes on, when I let off the gas the SES light goes out, but the truck is running great. I am going to change fuel filter, oil and filter next. Is there any way to tell if someone used a tuner on the truck and left a tune on it?

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